The order, which will not name specific countries or companies, has been under consideration for more than a year but has repeatedly been delayed, sources said.

WASHINGTON (Reuters) - President Donald Trump is expected to sign an executive order this week barring U.S. companies from using telecommunications equipment made by firms posing a national security risk, paving the way for a ban on doing business with China's Huawei, three U.S. officials familiar with the plan told Reuters.

The order, which will not name specific countries or companies, has been under consideration for more than a year but has repeatedly been delayed, the sources said, asking not to be named because the preparations remain confidential. It could be delayed again, they said.

The executive order would invoke the International Emergency Economic Powers Act, which gives the president the authority to regulate commerce in response to a national emergency that threatens the United States. The order will direct the Commerce Department, working with other government agencies, to draw up a plan for enforcement, the sources said.

If signed, the executive order would come at a delicate time in relations between China and the United States as the world's two largest economies ratchet up tariffs in a battle over what U.S. officials call China's unfair trade practices.

Washington believes equipment made by Huawei Technologies Co. Ltd., the world's third largest smartphone maker, could be used by the Chinese state to spy. Huawei, which has repeatedly denied the allegations, did not immediately comment.

The White House and Commerce Department declined to comment.

The United States has been actively pushing other countries not to use Huawei's equipment in next-generation 5G networks that it calls "untrustworthy." In August, Trump signed a bill that barred the U.S. government itself from using equipment from Huawei and another Chinese provider, ZTE Corp.

In January, U.S. prosecutors charged two Huawei units in Washington state saying they conspired to steal T-Mobile US Inc trade secrets, and also charged Huawei and its chief financial officer with bank and wire fraud on allegations that the company violated sanctions against Iran.

The Federal Communications Commission in April 2018 voted to advance a proposal to bar the use of funds from a $9 billion government fund to purchase equipment or services from companies that pose a security threat to U.S. communications networks.

Federal Communications Commission chairman Ajit Pai said last week he is waiting for the Commerce Department to express views on how to "define the list of companies" that would be prohibited under the FCC proposal.

The FCC voted unanimously to deny China Mobile Ltd's bid to provide U.S. telecommunications services last week and said it was reviewing similar prior approvals held by China Unicom and China Telecom Corp.

The issue has taken on new urgency as U.S. wireless carriers look for partners as they rollout 5G networks.

While the big wireless companies have already cut ties with Huawei, small rural carriers continue to rely on both Huawei and ZTE switches and other equipment because they tend to be cheaper.

The Rural Wireless Association, which represents carriers with fewer than 100,000 subscribers, estimated that 25 percent of its members had Huawei or ZTE equipment in their networks, it said in an FCC filing in December.

At a hearing Tuesday, U.S. senators raised the alarm about allies using Chinese equipment in 5G networks.

The Wall Street Journal first reported in May 2018 that the executive order was under review. Reuters reported in December that Trump was still considering issuing the order and other media reported in February that the order was imminent.